The participants that had a symptom or a history of mental retardation (IQ < 70), serious head trauma, seizures or any other mental disorder, and participants on any medical treatment will be excluded. Participants with a family history (first degree relatives) of schizophrenia, bipolar disorder or schizoaffective disorder will also be excluded to avoid the negative effect of these disorders on cognitive functions. The same exclusion criteria will also be applied to the control group.